ugps: nmea: make sure date is valid

GPS time without date was previously used to set system date:
Tue Oct 10 11:48:21 2000 user.info kernel: [  108.786639] ugps: system time differs from GPS time by more than 5 seconds. Using 2000-10-10T10:48:21 UTC as the new time
Tue Oct 10 11:49:27 2000 user.info kernel: [  174.794699] ugps: system time differs from GPS time by more than 5 seconds. Using 2020-05-26T10:49:27 UTC as the new time

Fix this by ignoring incomplete dates and wait for complete time
information before adjusting system date/time.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

package/utils/ugps/Makefile

@@ -12,9 +12,9 @@ PKG_RELEASE:=1
 
 PKG_SOURCE_URL=$(PROJECT_GIT)/project/ugps.git
 PKG_SOURCE_PROTO:=git
-PKG_SOURCE_DATE:=2020-04-29
-PKG_SOURCE_VERSION:=db40e3a22599641be68c88ece287d3fbbacd8a45
-PKG_MIRROR_HASH:=0ad8b1265ef3de880f0d7623bcf504e7976df8ee06d64e92f896f2e2a6030c39
+PKG_SOURCE_DATE:=2020-05-29
+PKG_SOURCE_VERSION:=0c54380e3d8920100fcfd41f0a1fe9872eb37d0e
+PKG_MIRROR_HASH:=cf7e5af73f9feabf643f988c040fd3783dc44c6f4b1ecada0957d4ee3d67c14e
 
 PKG_MAINTAINER:=John Crispin <john@phrozen.org>
 PKG_LICENSE:=GPL-2.0+